Fine Tuning a 360 Magnum with a Brawler "Double Pumper"

The T slot being square is a starting point and can vary slightly. That’s ok. If you need more air but not fuel you can get bypass air from other sources (like pcv or secondary butterflies or some guys drill holes in the primary butterflies, I personally don’t see the need for that). But you don’t want to be too far off of square or slightly rectangular. The T slot kinda acts on its own and tuning the idle (air or fuel side) only has marginal effects on the T slot. Your carb on your engine may not need that level of tuning. Usually this type of tuning is reserved for racier, big cam, big carb stuff.